1. Field of the Invention
The invention relates to an optical information reader including a code scanner, a two-dimensional code scanner, or a multi-code scanner picking up an image of a code symbol such as a barcode or a two-dimensional code composed of patterns having different light reflectances and reading out information indicated by the code symbol from the picked up image, and an optical information reading method of reading out the information indicated by the code symbol as described above.
2. Description of the Related Art
Conventionally, a code symbol such as a barcode or a two-dimensional code indicating information by a symbol different in light reflectance from surroundings is widely used as an automatic recognition means for article, document, material, specimen, and other various substances in a wide range of fields such as distribution, mail service, medical service, chemical experiment, and event site.
For example, when an article such as a merchandise or baggage having a code symbol attached thereto is put on a belt conveyor and moved to a predetermined place in an inspection process or distribution process, the code symbol attached to the article is read by a code scanner and the read information is transmitted to a host computer, which checks the contents of the article, records its progress, confirms distribution place and distribution time and so on.
Then, when reading the code symbol, it is necessary to accurately capture the code symbol moving on the belt conveyor and precisely decode the information indicated by the code symbol.
Further, for reading the code symbol, a code scanner which uses a solid-state image sensing element such as a CMOS sensor or a CCD sensor, is widely used as an optical reader.
As one conventional technique of the above-described optical reader, as described in PTL1 (see below), there is a technique wherein an image of a moving barcode is picked up by a plurality of image pickup elements arranged in two dimensions, the moving distance of the barcode in an exposure time in the image corresponding to output values of the image pickup elements is calculated by converting the moving distance into the number of image pickup elements, a static image of the barcode is restored from a portion including the barcode in the aforementioned image using the moving distance and a difference value between the output values of the image pickup elements adjacent to each other, and the restored barcode is decoded, whereby the barcode is read from a barcode image blurred due to movement.
Further, as another conventional technique, as described in PTL2 (see below), there is a technique wherein image pickup is tried several times until reading of information on a moving information code is successful, the conditions such as brightness of illumination and the like upon success are stored, and actual code reading is performed based on the conditions.
Furthermore, a commonly used digital camera using a solid-state image sensing element such as a CMOS sensor or a CCD sensor complies with a specification to enable, in a certain degree, picking up an image of a moving object as described in PTL3 (see below).    PTL1: Japanese patent laid-open publication No. 2002-230477    PTL2: Japanese patent laid-open publication No. 2004-110668    PTL3: Japanese patent laid-open publication No. 2006-197393